Many communication systems of different types and sizes are available today. A tendency is that the number of network nodes grows fast, which results in large complex network structures and topology. This is caused, partly because of the increasing traffic and partly on that the networks are requested to cover larger and larger geographical areas. Communication networks having nodes at all continents are present today. However, the more nodes and the more traffic that is to be transmitted, the more complex the configuration of the networks becomes.
A Virtual Private Network (VPN) utilises a public or private communications network to conduct private communications. Traditionally, a company or other customer that wanted to build a wide-area network had to provide for its own dedicated lines between each node to provide the connectivity. Such solutions are, however, generally expensive and inflexible. Conventionally, a VPN is created according to an agreement between a network operator and a customer. When having more and more complex communications networks, e.g. multi-domain networks, configuration becomes more and more complex and time consuming.
The general trend in communication network development goes to more and more flexible solutions. Mobile and wireless communication technologies are used, not only between different end terminals and a network, but also between different network parties. In such solutions, the different parties have responsibility for a respective communication system domain. The flexibility in connecting and disconnecting entire part networks, such as entire domains, makes situations, where a network continuously changes its appearance, more and more common. The task of communication configuring in such a dynamic network, e.g. the configuring of VPNs becomes extremely difficult since the available connection conditions between domains are continuously changing. In order to find optimum or at least well-operating solutions, the different domain operators always have to be updated about any changes in entire network topology.
One solution of the problem is to introduce a main controller node for the entire multi-domain communications system that is always updated, i.e. a hierarchical top structure. However, if the different domains are operated by different operators, not legally associated to each other, it may not be obvious that all information from one domain should be unconditionally available for such a main controller node. It might also be organizationally difficult for certain operators to be dependent on a main controller operator also for managing of their own domains. In most operator cooperation agreements, the operators are typically equal partners, where their relations are governed by mutual agreements. Furthermore, if the main controller node breaks down, the entire access to system-wide connection information vanishes.